Liquid fuel burner

ABSTRACT

A liquid fuel burner in which a mixture of atomized liquid fuel and pre-heated air is burned on the surface of a heat-radiant cylinder and the resultant combustion gases are introduced into the interior of said radiant cylinder, whereby the unburned gas present in the combustion gases is completely burned by contact with heated rods arranged in said radiant cylinder.

United States Patent [191 Murase et al.

[ 1 May 22, 1973 LIQUID FUEL BURNER Inventors: Shigeo Murase, Takatsuki-shi; Mituhiro Imajima, Yamatokoriyama-shi,

both of Japan Assignee: Matsushita Electric industrial Co.,

Ltd., Osaka, Japan Filed: Aug. 6, 1971 Appl. No.: 169,608

Foreign Application Priority Data Aug. 12, 1970 Japan ..45/7099l Oct. 29, 1970 Japan ..45/96l63 US. Cl. ..43l/88, 431/208, 431/211,

431/329, 431/347, 431/353 Int. Cl ..F23n 5/24 Field 01 Search ..43l/88, 195, 198,

[56] References Cited UNITED STATES PATENTS 1,532,612 4/1925 Taylor ..431/347 2,568,763 9/1951 Ray ...431/208 3,314,411 4/1967 Power ..431/88 3,391,983 7/1968 Harazono et al. .431/329 3,418,979 12/1968 Reichmann ..43l/328 Primary Examiner-Carroll B. Dority, Jr. Att0mey--Stevens, Davis, Miller & Mosher [57] ABSTRACT A liquid fuel burner in which a mixture of atomized liquid fuel and pre-heated air is burned on the surface of a heat-radiant cylinder and the resultant combustion gases are introduced into the interior of said radiant cylinder, whereby the unburned gas present in the combustion gases is completely burned by contact with heated rods arranged in said radiant cylinder.

5 Claims, 5 Drawing Figures PATENTEll-wz-glszg SHEET 2 OF 3 FIG. 2

FIG. 5

LIQUID FUEL BURNER BACKGROUND OF THE INVENTION Liquid fuel is widely being used because it is less expensive than other fuels or electricity. On the other hand, heating and not water supply-facilities are becoming larger and larger in size (in heating capacity) and, under the circumstances, a combustion apparatus is desired which takes a small space but has a larger heating capacity. As the heating capacity increases, the generation of soot, noise and toxic gases becomes a problem.

Therefore, a burner which is the critical element of such a combustion apparatus is required to be small in size, large in heating capacity and capable of burning fuel with no soot, no noise and no toxic gases.

Conventional burners of this type have the following problems:

1. High Load Combustion Because of being heated to high temperatures, the critical portion of the burner must be made of a heatresistant material. When metals are used as the heatresisting material, the temperature of the burner must be maintained within a certain range. Namely, it has been impossible to allow the temperature of the burner to rise above 900 C. On the other hand, when ceramics or bricks are used as the heat-resistant material, the temperature of the burner can be further elevated but the volume of the burner becomes large, and repetetive lighting and extinguishing results in spoiling of the refractory material.

2. Gasification For gasifying liquid fuel, the liquid fuel must be atomized by applying heat thereto. Further, for burning the atomized fuel, the burning part must be pre-heated so as to avoid condensation of fuel gas. Various methods have been used for the pre-heating of the burning part but it has been difficult to maintain the temperature of the burning part at a level suitable to cause the atomization of liquid fuel and further the pre-heating has resulted in generation of carbon or tars. Therefore, the conventional burners have involved such problems as accumulation of carbon, clogging of a gasifying pipe and clogging of the nozzles. In addition, pre-heating has been laborious and time-consuming.

3. Soot The combustion of liquid fuel is accompanied by the generation of soot. Therefore, the conventional bumers have had the disadvantages that the thermal efficiency is lowered by the soot generated and that much labor is required for the removal of soot.

4. Noise The combustion of a large amount of fuel in a small combustion chamber is accompanied by a large combustion noise. Particularly when the burner is used domestically, the combustion noise has an adverse affect on the living comfort and is a serious problem.

SUMMARY OF THE INVENTION The object of the present invention is to overcome such defects of the conventional burners as set forth above. Namely, the present inventors have made various attempts to burn liquid fuels in a gaseous state, and

obtained a liquid fuel burner based on a novel combustion process.

The features of the liquid fuel burner according to the present invention lie in (1) that liquid fuel is atomized and burned in a gaseous state, (2) that the combustion of the liquid fuel is spontaneously shifted from the stage of pre-heating the necessary parts of the burner to the stage of burning the fuel in a completely gasified state and no special means is required to effect such shifting, (3) that owing to a unique fumace-type heating, construction and the gasification of liquid fuel, the burner is small in size but generates a large amount of heat, (4) that owing to the unique furnace-type heating construction and the gasification of liquid fuel, a perfect combustion free of atmospheric pollution can be achieved, (5) that while the burner is small in size and high in heating efficiency, no soot is generated since the fuel is burned in the mode of blue flame combustion, and (6) that while the burner is small in size and high in heating efficiency, it causes no noise since the fuel is burned in such a manner as to form a large number of small flames at a larger number of apertures formed in the wall of a radiant cylinder.

The above-described features of the present invention establish the way that future liquid fuel burners for domestic as well as business use should be constructed, facilitating a reduction in size as well as a reduction in the cost of the burners and promoting the wide use of such burners.

According to the present invention there is provided a liquid fuel burner comprising centrifugal liquid fuel atomizing means, a burner case having said atomizing means disposed therein and open at the upper end thereof, an outer cylinder connected to the open end of said burner case, a heat-resistant cylinder disposed in the interior of said outer cylinder so as to define a gas passage between it and said outer cylinder, and a plurality of spaced heat-resistant rod members circularly arranged within said heat-resistant cylinder, the arrangement being such that a gaseous mixture of liquid fuel, atomized by said centrifugal atomizing means, and air is led into said gas passage and burned during passage through said heat-resistant cylinder and said heatresistant rod members.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a vertical sectional view of an embodiment of the liquid fuel burner of the present invention which is of an electric pre-heating type;

FIG. 2 is a sectional view of the essential portion of the burner taken along the line 11-" of FIG. 1;

FIG. 3 is a vertical sectional view of another embodiment of the liquid fuel burner of the invention which is of a pot pre-heating type;

FIG. 4 is a sectional view showing in an enlarged scale the gasifying part of the burner shown in FIG. 3; and

FIG. 5 is a sectional view taken on the line V-V of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid fuel burner of the invention which is of an electric pre-heating type, will be ignates an outer cylinder consisting of a heat-resistant.

heat transmitting cylinder made of heat-resistant glass or the like material, or a metallic cylinder made from an iron plate or casting. In the outer cylinder 1 is disposed concentrically a radiant cylinder 2 consisting of a heat-resistant metal net, punched metal or ceramic. Further, a plurality of heat-resistant rod members 3 are circularly arranged within the radiant cylinder 3 with a predetermined interval between each other, said heatresistant rod members consisting of rods of a heatresistant porous material acting as a catalyst, such as alumina rods or ceramic rods, or of glass rods or metal rods.

Reference number 4 designates a top closure member closing the upper opening of a passage 5 for a mixture of gasified liquid fuel and air, defined by the outer cylinder 1 and the radiant cylinder 2. Reference numeral 8 designates a bottom plate closing the lower open end of the radiant cylinder 2. Reference numerals 6, 7 designate supporting plates supporting the upper ends and the lower ends of the rod members 3 respectively. Reference numeral 9 designates a burner case open at the upper end, and the outer cylinder 1 is mounted on the upper open end of said burner case.

The lower portions of the radiant cylinder 2 and the rod members 3 are located in the burner case 9 and a vaporizing chamber 11 is formed between the lower portion of the radiant cylinder 2 and the burner case 9 for gasifying liquid fuel. The outer wall portion of the burner case 9 surrounding the vaporizing chamber 11 is shielded by a heat insulator 10.

Reference numeral 12 designates a motor and 31 designates the shaft of said motor. A fan blade member 13 is mounted on the upper end of the motor shaft 31 and further a centrifugal plate 18 is mounted on said motor shaft above said fan 13. The fan blade member 13 and the centrifugal plate 18 are all located within the burner case 9. A pump blade member 14 is mounted on the lower end of the motor shaft 31. This pump blade member 14 is disposed in a casing 29 of a pump 32 provided in a fuel tank 20, and submerged in liquid fuel 21 stored in the fuel tank 20. The rotation of the motor 12 is transmitted to the pump blade mem ber 14 through speed reduction means (not shown).

Reference numeral 22 designates an auxiliary fuel tank communicating with the fuel tank 20 by an overflow pipe 23. The auxiliary fuel tank is provided for the purpose of enabling the fuel to be supplied at a constant rate irrespective of a change in rate of rotation of the motor caused by a change in viscosity of fuel and a fluctuation of voltage. Reference numeral 19 designates a heating member consisting of a metal net, which is secured to the lower portion of the radiant cylinder 2 and separating the space around the centrifugal plate 18 and the vaporizing chamber 11 from each other. Reference numeral 24 designates a discharge pipe extending from the pump 32 to the auxiliary fuel tank 22.

Reference numeral 25 designates a fuel supply pipe extending from the auxiliary fuel tank 22 to the centrifugal plate 18. A flow regulating valve 26 is provided intermediary of the fuel supply pipe to regulate the supply of fuel through said fuel supply pipe. Reference numeral l7 designates a pre-heating heater provided upstream of an air inlet port formed in the bumer case 9, 33 an air inlet port, 34 a combustion gas exhaust opening, 16 a fuel inlet port of the pump, 28 a strainer and 27 a drain pipe.

In the burner constructed as described above, when a current is conducted through the motor 12 and the preheating heater 17, the fan blade member 13, the centrifugal plate 18 and the pump blade member 14 start rotating. Air sucked from the air inlet port 33 is pre-heated by the preheating heater 17. The pre-heated air flows into the burner case 9 and thence into the vaporizing chamber 11 through the heating member 19. Thus, the air passage is heated by the hot air. Then, the flow regulating valve 26 is opened and the degree of opening of the valve is adjusted so that a suitable mix ing ratio of air and fuel may be obtained. The fuel discharged onto the centrifugal plate 18 is splashed into the hot air stream under influence of centrifugal force and atomized.

The atomized fuel contacts the hot air and abuts against the heated burner case 9. Thus, the fuel is gasified in the vaporizing chamber 11. The gasified fuel and the air are mixed and the gaseous mixture flows into the passage 5. When the gaseous mixture is ignited by suitable means in the vicinity of the radiant cylinder 2, it burns with a number of small flames formed at a large number of pores on the surface of the radiant cylinder 2 and the radiant heat 2 is red-heated. The unburned gas flows into the radiant cylinder 2. On the other hand, the rod members 3 are heated to a high temperature by the heat of the red-heated radiant cylinder 2. The current supply to the pre-heating heater 17 is interrupted upon ignition of the mixture but, since the lower portion of the radiant cylinder 2 is located in the burner case 9, the burner case 9 is sufficiently heated by the radiant heat of the radiant cylinder 2 and the atomized fuel is sufficiently gasified. Once this condition has been reached, the amount of fuel being burned greatly increases.

The unburned gas which has not been burned by the radiant cylinder 2 forms a turbulent flow by being stirred by the rod members 3 and is thoroughly mixed with air. Therefore, the combustion rate of the unburned gas is accelerated and the unburned gas is completely burned around and interior of the rod members 3. The combustion gas is exhausted from the exhaust opening 34. As a result, the rod members 3 are further heated red-hot to a temperature higher than that of the radiant cylinder 2 and form a sort of heating furnace. Where ceramic rods are used for the rod members 3, an oxidation reaction takes place in the atmosphere within the heating furnace, so that the heating furnace generates no noise though it is small in volume and generates a large amount of heat.

Since the radiant cylinder 2 and the rod members 3 are thus heated to high temperatures, the atmospheric temperature in the vaporizing chamber is elevated and the internal temperature of the burner case 9 is also elevated by the radiant heat. Further, the temperature of the heating member 19 is also elevated by the heat conducted thereto. Under such condition, the atomized fuel is heated by the heating member 19 and completely gasified by contact with the burner case 9. Thus, a large amount of infrared rays (heat rays) are radiated from the radiant cylinder 2 and, where the outer cylinder 1 is a heat-resistant heat transmitting cylinder, the infrared rays radiate to the outside through said cylinder.

The radiant cylinder 2 provides a heating source for the rod members 3 at the time of ignition and thereafter serves to uniformly supply the unburned gas to the rod members by dividing it into a number of fine streams. It also serves to promote the atomization of fuel and becomes an infrared ray radiating source.

The rod members 3 accelerates the combustion rate and thereby makes it possible to burn a large amount of fuel. When heated to a high temperature, the rod members 3 promote the gasification of fuel and become an infrared ray radiating source. In this burner, a large amount of fuel can be gasified instantaneously. Therefore, by accelerating the combustion rate, it becomes possible to increase the amount of fuel to be burned per unit volume of the combustion chamber and unit time. Namely, a high load combustion becomes possible.

In the burner of the invention having the construction described above, since the rod members 3 are provided in the interior of the radiant cylinder 2, it is possible to burn an amount of fuel about twice as large as that which can be burned in the conventional burners of this type. Namely, the combustion rate can be drastically increased, whereby a large amount of fuel can be burned in the small combustion part and a large amount of radiant heat can be radiated from said combustion part. Furthermore, since the lower ends of the radiant cylinder 2 and the rod members are located within the burner case 9, so as to maintain the interior of the burner case 9 at a high temperature, a large amount of liquid fuel can be gasified quickly and a satisfactory combustion can be expected. Therefore, the soot and noise problems mentioned previously can be completely solved by employing the burner of the invention.

Now, another embodiment of the liquid fuel burner of the invention which is of a hot pre-heating type will be described with reference to FIGS. 3-5. In FIGS. 3-5, parts same as those of the preceding embodiment are indicated by the same reference numerals and the description thereof will be omitted, and the differences only between both burners will be described hereunder: In this embodiment, a pot-type burner element 35 is mounted on the lower open end of the radiant cylinder 2 in such a manner as to close said open end. This pot-type burner element has an outer wall 42 with a plurality of apertures 36 formed therein and an inner wall 37 defining a central opening 38. A cup-shaped cap 40 is removably mounted over the opening 38, with a slight gap between its peripheral wall 43 and the inner wall 37 of the burner element 35. The peripheral wall 43 of the cap 40 has fuel passage apertures formed therein. The centrifugal plate 18 is disposed interior of the cap 40 at a level slightly higher than the inner wall 37 of the burner element 35 and the fuel supply pipe 25 is extended with its end located above the centrifugal plate 18. An electromagnetic valve 41 incorporating a mercury switch, etc. is provided intermediary of the fuel supply pipe 25, so that when the burner is subjected to an earthquake shock or other external vibrations, said electromagnetic valve 41 may be actuated to interrupt the supply of fuel. The electromagnetic valve 41 may be used in the preceding embodiment in the same way as in this embodiment. The heating member 19 used in the preceding embodiment is unnecessary in this embodiment.

In the construction shown in FIGS. 3-5, when a current is conducted through the motor 12 and the preheating heater (not shown), the fan blade member 13, the centrifugal plate 18 and the pump blade member l4 start rotating. Therefore, air sucked from the air inlet port 33 is pre-heated by the pre-heating heater and flows into the burner case 9 through the air inlet port 15, whereby the passage in which the pre-heated air passes is heated. Then, the flow regulating valve 26 is opened and the degree of opening thereof is adjusted so that a suitable mixing ratio of air and fuel may be obtained. The fuel discharged on the centrifugal plate 18 is splashed and atomized under the influence of centrifugal force. The atomized fuel falls into the gap between the inner wall 37 of the burner element 35 and the peripheral wall 43 of the cap 40, reaches the bottom of the burner element 35 through the fuel passage apertures 39 and moves upward along the inner surface of the outer wall 42 of said burner element 35. On the other hand, the pre-heated air flows into the burner element 35 through the apertures 36 formed in the outer wall 42 of the burner element 35 and mixed with the atomized fuel. When the mixture is ignited by suitable means within the burner element 35, it burns and the cap 40 is heated thereby. Therefore, the atomized fuel present in the cap 40 is gasified. The gasified fuel is mixed with the hot air supplied through the central opening 38 of the burner element 35 and the mixture flows into the passage 5. The mixture burns with a number of small flames formed at a large number of the pores on the surface of the radiant cylinder 2 and thus the radiant cylinder 2 is red-heated. The function of the rod members 3 and the state of combustion subsequent to this point are the same as in the preceding embodiment.

When the burner undergoes an earthquake shock or other external vibrations during use and a danger of tire arises, the mercury switch or the like senses the vibration and shuts down the electromagnetic valve 41, whereby the burner can be extinguished instantaneously.

In either embodiment described above, it is preferable to use a glass cylinder for the outer cylinder 1 so that the interior of the burner may be visible from the outside, to use a metal net cylinder for the radiant cylinder 2 so that said radiant cylinder may be uniformly red-heated, and to use alumina rods, ceramic rods or other rods which act as catalyzer for the rod members 3 so that the combustion may be carried out by oxidation reaction.

The burner of the invention constructed as described herein in small in volume and high in heating capacity, and yet further, radiates infrared rays from the radiant cylinder 2 to the outside through the outer cylinder 1..

Therefore, the heating efficiency of the burner is high.

At the same time, it also has a great visual heating effect since the red-heated state of the radiant cylinder 2 is visible from the outside.

We claim:

1. A liquid fuel burner comprising centrifugal liquid fuel atomizing means, a burner case having said atomizing means disposed therein and open at the upper end thereof, an outer cylinder connected to the open end of said burner case, a heat-resistant cylinder disposed in the interior of said outer cylinder so as to define a gas.

passage between it and said outer cylinder, and a plurality of spaced heat-resistant rod members circularly arranged within said heat-resistant cylinder, the arrangement being such that a gaseous mixture of liquid fuel, atomized by said centrifugal atomizing means, and air is led into said gas passage and burned during passage through said heat-resistant cylinder and said heatresistant rod members.

2. A liquid fuel burner as defined in claim 1, wherein the lower end of the heat-resistant cylinder is located within the burner case and the upper end of the outer cylinder excepting for the circular portion defined by the upper ends of the circularly arranged heat-resistant rod members is closed.

' an electromagnetic valve is provided intermediary of a fuel supply pipe leading to the centrifugal liquid fuel atomizing means, said valve being adapted to shut down said fuel supply pipe upon sensing a vibration.

5. A liquid fuel burner comprising a motor, a motor shaft, a fan blade member and a centrifugal plate mounted on one end of said motor shaft, a blade member of a fuel pump mounted on the other end of said motor shaft, a fuel supply pipe for supplying liquid fuel from said fuel pump through an auxiliary tank to said centrifugal plate, an over-flow pipe connected to said auxiliary tank, a heat-resistant heat transmitting outer cylinder connected above a burner case in which said fan blade member is disposed, a heat-resistant metal net cylinder disposed interior of said outer cylinder and heat-resistant rod members disposed interior of said heat-resistant metal net cylinder and acting as catalyzer, the arrangement being such that a gaseous mixture of liquid fuel, supplied onto said centrifugal plate by said fuel pump and atomized by said centrifugal plate, and air is burned during passage through said heat-resistant cylinder and said heat-resistant rod members. 

1. A liquid fuel burner comprising centrifugal liquid fuel atomizing means, a burner case having said atomizing means disposed therein and open at the upper end thereof, an outer cylinder connected to the open end of said burner case, a heatresistant cylinder disposed in the interior of said outer cylinder so as to define a gas passage between it and said outer cylinder, and a plurality of spaced heat-resistant rod members circularly arranged within said heat-resistant cylinder, the arrangement being such that a gaseous mixture of liquid fuel, atomized by said centrifugal atomizing means, and air is led into said gas passage and burned during passage through said heatresistant cylinder and said heat-resistant rod members.
 2. A liquid fuel burner as defined in claim 1, wherein the lower end of the heat-resistant cylinder is located within the burner case and the upper end of the outer cylinder excepting for the circular portion defined by the upper ends of the circularly arranged heat-resistant rod members is closed.
 3. A liquid fuel burner as defined in claim 1, which further comprises a pot-type burner element mounted in such a manner as to close the lower end of the heat-resistant cylinder and having an opening centrally thereof, and a cap mounted in such a manner as to cover said opening from the upper side and having fuel passage apertures formed in the lower portion of the peripheral wall thereof, said cap having the centrifugal liquid fuel atomizing means disposed therein.
 4. A liquid fuel burner as defined in claim 1, wherein an electromagnetic valve is provided intermediary of a fuel supply pipe leading to the centrifugal liquid fuel atomizing means, said valve being adapted to shut down said fuel supply pipe upon sensing a vibration.
 5. A liquid fuel burner comprising a motor, a motor shaft, a fan blade member and a centrifugal plate mounted on one end of said motor shaft, a blade member of a fuel pump mounted on the other end of said motor shaft, a fuel supply pipe for supplying liquid fuel from said fuel pump through an auxiliary tank to said centrifugal plate, an over-flow pipe connected to said auxiliary tank, a heat-resistant heat transmitting outer cylinder connected above a burner case in which said fan blade member is disposed, a heat-resistant metal net cylinder disposed interior of said outer cylinder and heat-resistant rod members disposed interior of said heat-resistant metal net cylinder and acting as catalyzer, the arrangement being such that a gaseous mixture of liquid fuel, supplied onto said centrifugal plate by said fuel pump and atomized by said centrifugal plate, and air is burned during passage through said heat-resistant cylinder and said heat-resistant rod members. 